Ultraviolet light treatments for increasing seed yields

ABSTRACT

UV light treatment increases harvested seed yield. UV treatment in combination with chemical treatment also increases seed yield. UV treatment of corn, soybean, and wheat varieties resulted in enhanced harvested seed yield. Hormetic response, disinfection, disinfestations, and other factors are induced by UV treatments.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority to U.S. patent application Ser. No. 12/357,760, filed Jan. 22, 2009, and U.S. provisional application No. 61/247,191, filed Sep. 30, 2009, the contents of which applications are herein incorporated by reference in their entireties.

BACKGROUND

Increasing harvested seed yield from plants is important to nourish a continuously growing population on diminishing arable land. Seed yields are dependent on a multitude of environmental factors and on the genetic response of a plant to these factors. In general, conditions optimum for plant growth and development are not necessarily optimum conditions for harvested seed production, which has its own set of optimum environmental and biological factors such as conditions for pollination. Therefore, increase in plant biomass does not necessarily result in an increased harvested seed yield.

The growth and reproduction of a plant is dependent on abiotic (physical) and biotic (biological) factors. Abiotic factors include physical environmental conditions and biotic factors include animals, insects, and diseases. Each plant has certain environmental requirements for optimum growth including temperature, light, moisture, growth medium, and the level of medium fertility. Suboptimum conditions for any of these factors can result in reduced plant growth and/or reduced harvested seed yields.

A type of ultraviolet light (UV-C light), which is light with a wave length of 100-290 nm and predominately in the 254 nm range, and other physical stressors, are known to elicit resistance to pests in plants. Use of UV-C light and other physical stressors was originally expected to reduce harvested seed yield because it was generally believed that extra energy would be expended in “turning on” host resistance responses. Consequently, by treating sowing seeds with UV light a reduced yield of harvested seed would be expected.

Pulsed UV light, which is UV light delivered in short microsecond wide pulses, is a method presently used in delivering light for the decontamination of surfaces, primarily in the food and pharmaceutical processing industries. In these instances short, high frequency pulses of an intense broad spectrum of light with a predominance of UV-C are applied. With these systems the light is delivered with a high peak power and consists of wavelengths from 200 to 1100 nm predominately in the UV-C range of 200-280 nm. Lagunas-Solar et al. (U.S. Pat. No. 5,364,645) discloses delivering a monochromatic beam of pulsed ultraviolet laser radiation of a wavelength of 240-280 nm with pulsed durations in the range of picoseconds to microseconds at 1-1900 mJ/cm².

Because of concerns for safety to man and the environment, considerable opposition to the use of synthetic pesticides and/or increased use of fertilizer in crop production has developed. This has created a demand for “greener” technologies that are less harmful to mankind and the environment. The UV treatment to increase harvested seed yields disclosed herein offers such an ecologically friendly “green” technology.

SUMMARY

A method of increasing the yield of harvested seed includes treating sowing seeds with UV-C light or other equivalent physical stressors and, optionally, in combination with an over-treatment with chemicals, such as, for example, one or more chemical pesticides. Without being bound by a particular theory or mechanism, the increased yield in harvested seeds is likely to be produced in large part by a hormetic response within the seeds elicited by UV-C light and also may, in part, be due to the added and/or synergistic effects of disinfestation and disinfection of pests associated with the seeds.

Methods and compositions disclosed herein provide delivery of effective doses of UV-C light to the surfaces of sowing seeds during processing. In an embodiment, a method of delivering light to sowing seeds (primarily in the UV-C range of 200-300 nm) is by utilizing continuous wave UV light, pulsed UV light, or pulsed UV laser light in order to enhance the yield of harvested seed. Pulsed UV light or pulsed UV laser light is more intense and consequently provides increased penetration power as compared with e.g., UV light emitted from conventional continuous wave mercury vapor lamps. Regardless of the manner in which the UV light treatment is applied, optimal treatments are disclosed or described to maximize harvested seed yield.

A method of increasing the yield of harvested plant seeds includes treating plant seeds with an effective dose of ultraviolet (UV) light. The UV light includes UV-C. In an embodiment, the UV light is pulsed UV. Effective doses of UV range from about 0.025-480 kJ/m².

In an aspect, the pulsed UV light includes a high peak power of wavelengths from about 200 to 1100 nm. In an embodiment, the pulsed UV light is substantially in the UV-C range of about 200-280 nm. In an embodiment, the pulse durations range from picoseconds to microseconds at 1-1900 mJ/cm².

In an aspect, the yield increase for harvested seeds treated by the methods described herein is by about 5%-10% when compared to untreated control seeds.

In an aspect, UV treatment of seeds is coupled with treating the seeds with a chemical. The chemical treatment includes, for example, pesticides, insecticides, and fungicides or a combination thereof.

Suitable plant seeds include crop plants such as soybean, corn, wheat, rice, cotton, sorghum, canola, and vegetables.

In various aspects, one side, two sides or the ends of the seeds are exposed to the UV light. In an aspect, the UV light is from a pulsed laser light source.

A method of treating a plurality of plant seeds with a physical stressor to induce a hormetic response is disclosed, wherein the physical stressor is UV light and the hormetic response is increased harvested seed yield.

A plurality of UV light-treated plant sowing seeds are described such that the sowing seeds result in plants whose harvested seed yield is increased, whereby the UV light treatment is effective to induce a hormetic response.

A plurality of UV-C light-treated sowing plant seeds, are described wherein the UV-C light is effective to induce an increased yield of the harvested seeds. In an aspect, the UV-C light-treated sowings are also treated with an agent. Suitable agents include pesticides, insecticides, and fungicides.

DETAILED DESCRIPTION

Methods are disclosed to increase harvested seed yield for a variety of plant species by exposing the sowing seeds to UV light. UV exposure coupled with chemical over-treatments also increase harvested seed yield. Continuous UV light or pulsed UV light treatments at various energy levels increase harvested plant seed yield.

Many plant species showed benefits of methods described herein. By treating soybean sowing seeds with select doses of UV-C light, a positive hormetic response was triggered that resulted in enhanced yields of harvested seeds. By treating corn, soybean, and wheat sowing seeds with select doses of UV-C light, coupled with over-treatment with conventional chemical seed treatment(s), a positive hormetic response was triggered that resulted in enhanced yield of harvested seeds. In another aspect, the UV-C light treatments were applied with a conventional continuous wave mercury vapor lamp. In another aspect, UV-C light delivered by a pulsed light system is also suitable to trigger a positive hormetic response in sowing seeds. Similar amounts of UV-C energy are delivered by, for example: continuous wave mercury lamp, pulsed UV light, and pulsed UV laser light. Depending on the intensity of the light used, for example, a pulsed high-intensity UV light has greater energy and therefore is more penetrating. Therefore, a positive hormetic response is achieved with a lower dose of UV-C light from the pulsed systems than a comparable treatment dose from, e.g., a conventional continuous wave mercury vapor lamp system.

UV-C light alters the plant's DNA to get a positive hormetic response as measured by enhanced yield coupled with the added effects of disinfestation and disinfection of pests associated with the seeds. Determining an optimum UV-C light treatment level or a range for each type of UV-C light delivery system is described in the Materials and Methods section herein and is readily optimized by a person of ordinary skill in the art based on the guidance and disclosure provided herein. Broader ranges of wave lengths of light are also contemplated.

The term “seed”—(in some plants referred to as a kernel) as used herein, generally refers to a small embryonic plant enclosed in a covering called a seed coat with some stored food. Seed may also be used in general reference to any propagule (plant material used for propagation) that can be sown such as for example, a “seed potato” that includes a piece of a tuber.

The term “harvested seed” as used herein, generally refers to a seed gathered from a crop when it is ripe for consumption or for any other desired use. The term “sowing seed” as used herein generally refers to a plant seed that is dispersed over or under the ground or other growth medium to produce a crop or plant. Sowing seed is often treated with a coating of a pesticide to reduce root rots and insect infestation.

The term “hormesis (hormetic response)”—(from the Greek word “hormein” meaning to “excite”) as used herein generally refers to a principle whereby a generally-favorable biological response occurs to low exposures of a stressor. A stressor eliciting hormesis thus has the opposite effect in small doses than in large doses. A factor capable of exciting the favorable response is called a hormetin. UV-C light is a hormetin as used herein.

The term “disinfest (disinfestation)” as used herein generally refers to the process of removal or inactivation of pests (plant pathogens and insects) from plant surfaces.

The term “disinfect (disinfection)” as used herein generally refers to the process of killing microorganisms (fungi and bacteria) that have infected (established a food relationship) within a plant tissue.

Methods to enhance harvested seed yield disclosed herein provide effective UV light doses that are delivered to the surfaces of sowing seeds to minimize seed treatment processing times. In an aspect, pulsed UV light is used for a shorter processing time. Pulsed light systems deliver a broader spectrum of light (substantially in the UV-C range) with more penetrating photons. In an aspect, filters are used to increase the concentration of emitted UV-C light. Xenon Corporation's (Wilmington, Mass.) pulsed xenon arc lamp produces high peak power pulsed UV light at irradiance magnitudes and dose flux rates that induce complete microbial sterilization in a short period of time. By utilizing controlled high irradiance, UV light can be delivered in short microsecond-wide pulses at total doses in the order of 1.27 Joules/cm². This system produces increased sterility assurance levels than conventional sterilization technology delivered by mercury vapor lamps and is expected to deliver hormetic doses of UV light to sowing seeds in a shorter time. Also, a monochromatic beam of pulsed ultraviolet laser radiation of a wavelength of 240-280 nm is delivered with pulsed durations in the range of picoseconds to microseconds at 1-1900 mJ/cm².

In an aspect, treatment of soybean sowing seeds with a single treatment of a selected dose of UV-C light (a hormetin) in the range of 0.025-480 kJ/m² resulted in increased yield of harvested seeds (see Examples 3 and 4). Example 4 shows that three out of seven sowing soybean seed treatments with UV-C light and no chemical over-treatment resulted in an average yield improvement of 2.5 bushels per acre or 3.9 percent over the control. Soybean Variety #2, which responded the most positively to the UV-C light treatment without chemical over-treatment, demonstrated an average 5.9 bushels per acre or about 9.8 percent improvement in yield over the control.

In an aspect, treatment of corn, soybean, and wheat sowing seeds with a single treatment of a selected dose of UV-C light (a hormetin) in the range of 0.025-480 kJ/m² followed by treatment with one or more commonly used chemical pesticides as an over-treatment, resulted in increased yields of harvested seed from these crops (see Examples 1, 2, 5, 6 and 7). Example 1 shows an average 11.2 bushels per acre or 5.3% improvement in harvested corn yields from 3 different UV-C light treatments with chemical over-treatment on 2 different hybrids over the control. Example 2 shows an average 13.2 bushels per acre or 11.1% improvement in yield of a single corn inbred over the control from a single treatment of UV-C light with chemical over-treatment. Example 5 shows an average 2.2 bushels per acre or 3.5% improvement in soybean yield over the control for 7 different UV-C light treatments with chemical over-treatment on 3 different varieties. Example 6 shows an average 4.7 bushels per acre or 7.5% improvement in yield over the control for the 3 best UV-C light treatments for each of the 3 soybean varieties. The three best selected treatments of UV-C light for Soybean Variety #2 showed the most positive response with an average yield improvement of 5.6 bushels per acre or 9.2% over the control. Example 7 shows one of four different UV-C light treatments to wheat with chemical over-treatment resulted in enhanced yield that was 6.7 bushels greater than control or a 12.5% improvement in yield over control.

With the multiplicity of environmental and genetic factors required to increase harvested seed yield, it was not expected that a single physical sowing seed treatment with a stressor such as UV-C light would increase the yield of harvested seed. For example, abnormal amounts of a physical stressor such as heat, cold, wetness, or dryness to growing seed crops generally results in harvested seed yields that are below the normal. With the normal amount of UV-C light in the environment being negligible, it would be reasonable to expect that any dose of UV-C light would be an abnormal amount of a physical stressor to sowing seeds which would result in lower than normal yield of the harvested seed. Therefore, the observation that a single physical stressor UV light treatment enhanced harvested seed yield was surprising.

In addition, it has also been reported that the energy expended by plants in response to an elicitor of host defenses may actually lead to reduced yields of harvested seed by the plant (Heil et al. 2001, Journal of Ecology 88: 645-654). The “fitness costs” that are entailed when resistance is induced in plants is expected to result in reduced yields of harvested seed from the treatment of sowing seeds of corn, soybeans, and wheat with the elicitor of host resistance UV-C light. However, it was unexpectedly found that such treatments described herein significantly enhanced the yield of harvested seeds. The ability to enhance the yield of harvested seed of corn, soybeans, and wheat by the treatment of sowing seeds with selected doses of UV-C light coupled with a chemical over-treatment and the yield of soybeans without chemical over-treatment or the use of any other growth promoting chemical seed treatment is surprising.

Usage of higher UV-C light doses, as disclosed herein may provide a synergistic effect resulting in a greater yield increase than that produced by the additive effects of the UV-C light hormesis and disinfestation or disinfection alone. Selected doses of UV-C light in a range of 0.025-480 kJ/m² are likely to provide additional positive effects other than just hormesis.

Crop seeds are often treated with synthetic pesticides (fungicides and insecticides) to control root rots and insect infestations. Such treatments often increase crop yields through the control of these pests. In an embodiment, as shown in the Examples, treatment of sowing corn, soybean, and wheat seeds with selected doses of UV-C light followed by over-treating the seeds with chemical pesticides significantly increased the production of harvested corn, soybean, and wheat seeds, as compared to yields without the UV-C light treatment, but with the same chemical pesticides. Because the hormetic response elicited by UV-C light and other hormetins has been found in a wide range of plants and animals, this phenomenon appears to be highly conserved. Therefore, it can be expected that the method of using UV light treatment to increase harvested plant seed yield disclosed in this invention is likely to be applicable for a wide variety of plant species including all crop plants. These plant species include those that customarily use chemical seed treatments and the crop species that currently do not customarily use chemical seed treatments.

Suitable UV-C light doses for a non-pulsed mode of treatment are provided herein. Depending on the type of seeds, and possibly varieties or hybrids within seed types, optimal doses can be readily determined. According to the hormetic model, as the dosage of a stressor such as UV-C is increased there will be an optimum dosage that will give a maximum beneficial response, as measured by the yield of harvested seed. From results described herein, it is likely that the optimum treatment will be found in the range of 0.025-480 kJ/m². The specific optimal treatment is determined through treating sowing seed with UV-C light and field testing treated seed within this range for harvested seed yield. To expedite the determination of optimal treatments and to do so at a lower cost, treating sowing seeds with UV-C light in the range of 0.025-480 kJ/m² and planting them in a greenhouse where effects of the irradiation (positive and negative) on seedling growth can be observed, the number of necessary field trials can be narrowed. Further, by growing plants from UV-C treated seed in the greenhouse, inoculating them with a pest, such as Fusarium sp., and then observing the effects of the irradiation on disease development the number of field trials necessary for identifying optimal doses may be narrowed further.

Suitable UV-C light doses (kJ/m²) include for example 0.025, 0.050, 0.075, 0.01, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 2.0, 5.0, 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 480, 485, 490, 495, and 500 kJ/m² and intermediate doses thereof.

Suitable ranges of UV-C light doses (kJ/m²) include for example 0.025-10, 0.5-5, 1-10, 1-100, 10-100, 50-100, 100-200, 100-300, 100-400, 100-480, 100-500, 5-50, 25-250, 30-300, 40-400, 200-300, 200-400, 100-150, 150-300, and sub-ranges thereof.

Suitable ranges of UV-C light doses (kJ/m²) include for example less than 100, less than 200, less than 300, less than 400, less than 500, greater than 0.025, greater than 0.5, greater than 1, greater than 10, greater than 100, greater than 150, greater than 200, greater than 250, greater than 300, and greater than 400.

In an embodiment, one or more chemical over-treatments are combined with the UV-C treatment. The chemical treatment can be applied before, after, or along with the UV treatment. Depending on the type of seeds being subjected to UV treatment, the chemical treatment may vary. For example, for sowing corn seed the chemical over-treatments used were Maxim XL™ (fludioxonil and mefenoxam), Apron XL™ (mefenoxam), and Trilex™ (trifloxystrobing). For sowing soybean seed, the chemical over-treatment used was Apron Maxx™ (mefenoxam and fludioxonil). For sowing wheat seed, the chemical over-treatment used was Dividend Extreme™ (difenoconazole and mefenoxam).

The effectiveness of UV-C light in enhancing seed yields that are controlled by a multiplicity of factors may reside in the multiple effects of UV-C light irradiation on the seed. UV-C light elicits host resistance in plants to pests. UV-C light was able to disinfest the surface of corn and soybean seeds, as well as, disinfect internal infections of Fusarium sp. in these seeds. This multifaceted action of UV-C light may account for some of the findings that a single treatment of UV-C light of sowing seeds resulted in enhanced yields of harvested seeds.

Selected treatments of UV-C light from within a wide range of UV-C light doses from 0.025-480 kJ/m² applied to sowing corn, soybean, and wheat seeds resulted in enhanced yields of harvested corn, soybean, and wheat seeds. Increases in the yield may be due to hormesis, disinfestation, and disinfection of the seed, as well as, other unknown factors. Other doses of UV-C light outside the range of 0.025-480 kJ/m² that may enhance the yield of harvested seed are within the scope of this disclosure.

Example 4 shows that the three best of seven sowing soybean seed treatments with UV-C light and no chemical over-treatment resulted in an average yield improvement of 2.5 bushels per acre or 3.9 percent over the control. Variety #2, which responded most positive to the UV-C light treatment without chemical over-treatment, showed an average 5.9 bushels per acre or 9.8 percent improvement in yield over the control.

In some instances, the combined use of a selected plant physical stressor to induce the hormetic response in sowing seeds with the use of conventional chemical seed treatments is performed. Such combinations may yield additive and/or synergistic responses to plant pests and environmental stress that result in enhanced harvested seed yield.

In some instances, the use of a selected physical plant stressor to induce the hormetic response in sowing seeds without the use of conventional chemical seed treatments may result in enhanced harvested seed yield.

In an embodiment, UV-C light irradiation results in the disinfestation of plant seed surfaces. Such disinfestation can result in depressed disease development by seedborne pathogens, insects, and nematodes. Also, the combined action of a hormesis response in the seed with disinfestation results in additive and/or synergistic resistance of the plant to pests and environmental stress.

In an embodiment, UV-C light irradiation results in the disinfection of plant seed surfaces. Such disinfection can result in depressed disease development by seedborne pathogens, insects, and nematodes. Also, the combined action of a hormesis response in the seed with disinfection results in additive and/or synergistic resistance of the plant to pests and environmental stress.

Among the seeds where treatment of sowing seeds with a physical plant stressor such as UV-C light may lead to enhancement of harvested seed yields are the approximately 35,000 seed plants of the world including corn, soybeans, wheat, rice, cotton, peanuts, vegetable seeds, flower seeds, grass seeds, forest tree seeds, and nuts. Among the beans are chickpeas, cowpeas, dry beans, fava beans, lablab, lentils, lupines, peas, pigeon peas, velvet beans, vetch, winged beans, yam beans, and tonica beans. Among the cereals are barley, fonio, kamut, maize (corn), pearl millet, oats, palmer's grass, rye, sorghum, spelt, teff, triticale, breadnut, buckwheat, cattail, chia, cockscomb grain armaranth, kaniwa, pitseed goosefoot, quinan, and wattlesseed, Among the nuts are almond, beech, butternut, brazil nut, candlenut, cashew, chestnuts, colocynth, filbert, hickory, pecan, Indian beech, kola nut, macadamia, mamoncillo, maya nut, mongonogo, oak acorns, ogbono nut, paradikse nut, walnut, water caltrop. Among the nut-like gymnosperm seed are cycads, ginko, juniper, monkey-puzzle, pine nuts, and podocarps. Also included are alfalfa, red clover, flax, rapeseed, sugarcane, sugar beets, canola, cempedak, durian, equsi, fluted pumpkin, hemp seed, jackfruit, lotus seed, malaboar, gourd, pistachio, pumpkin seed, sunflower seed, and herb seed. Other plant propaguels, such as corms, tubers, bulbs, and rhizomes, and other plants not specified above would fall within the scope of this invention.

In the following examples corn, soybean, and wheat seeds were treated with a variety of doses of UV-C light in the range of 28-480 kJ/m². The corn hybrids were planted in 6 replicated blocks at one location and the inbred was planted in two replicated blocks at one location. The sowing seeds were planted in thirty-inch rows on ground prepared following conventional tillage practices. The prior year crop on this ground was soybeans.

The soybean varieties were planted in 3 replicated blocks at one location. The sowing seeds were planted in thirty-inch rows on ground prepared following conventional tillage practices. The prior year crop on this ground was soybeans.

The wheat variety was planted in 3 replicated blocks at one location. The sowing seeds were drilled in rows that were 6 feet 7 inches wide by 18 feet long on ground prepared following conventional tillage practices. The prior year crop on this ground was soybeans.

The methods and devices encompassed by the present disclosure include providing pulsed UV light and pulsed UV-C laser light to substantially reduce the processing time of traditional mercury vapor lamps that provide UV light. Accordingly, effective hormetic doses of UV-C light are delivered to seeds surfaces in seconds with pulsed UV light as opposed to for example, minutes and hours with conventional continuous wave mercury vapor lamps. Effective hormetic UV-C light doses can be delivered to seed surfaces in picoseconds to microseconds with pulsed UV-C laser light as opposed to minutes and hours with conventional continual wave mercury vapor lamps. This rapid delivery of effective hormetic dosages of UV-C light to sowing seed with pulsed light systems will allow this technology to be more readily integrated into present methods for processing seed.

Because the hormetic response elicited by UV-C light appears to be highly conserved in plants and enhances yield, this UV light treatment technology is applicable to a wide variety of additional seed crop species that customarily use chemical seed treatments and it may also be applicable to additional seed crop species that currently do not customarily use chemical seed treatments.

Positive responses (i.e., yield increases) are also possible at lower doses than the tested doses shown in the examples. It is also possible to include a multitude of doses within a treatment regimen instead of a single dose. For example, a treatment plan may include low doses initially followed by a progressive increase in the dose at varying lengths of time. Suitable time includes 1-10 minutes, 10-30 minutes, less than 1 hour and less than 2 or 3 hours. Pulsed UV light and pulsed laser light are applied to shorter durations such as 1 millisecond, 1 picosecond, 1 microsecond, 1 second, 10 seconds, 30 seconds, and sub ranges thereof. Dosages for pulsed UV light would include UV pulses (0-6) delivered in 360 microsecond pulses at 1.2 Joules/cm²/second. Dosages for pulsed UV laser light would include UV laser pulsed light delivered in 0-100 ns pulses with a wavelength between 240-280 nm and each pulse delivering 1 to 2 mJ/cm².

Some of the terms used to describe the pulsed UV light are mentioned herein. For example, fluence rate is measured in Watt/meter² (W/m²) and is the energy received from the lamp by the sample per unit area per second. Fluence is measured in Joule/meter² (J/m²) and is the energy received from the lamp by the sample per unit area during the treatment. Dose is used sometimes as a synonym of fluence. Exposure time is usually denoted in minutes or seconds and refers to the length in time of the treatment. Pulse width refers to the time interval (fractions of seconds) during which energy is delivered. Pulse-repetition-rate (prr) relates to the number of pulses per second (Hertz [Hz]) or commonly expressed as pps (pulses per second). Peak power is often measured in Watt (W) and is pulse energy divided by the pulse duration.

Chemicals or other agents that are used as pesticides, fungicides, insecticides for treatment of sowing seeds are suitable for use in conjunction with the UV treatments disclosed herein. Commercial doses may be reduced to reduce the amount of chemicals used. The seeds are treated with an agent either prior to or after the UV-C treatment.

A large amount of sowings seeds are treated by UV-C light in a high throughput fashion to supply the seeds for a large growing area.

It was found that certain selected doses of UV-C light (within the range of 0.025-480 kJ/m²) when applied to sowing seeds were effective in enhancing the yield of harvested corn, soybean, and wheat seeds as shown in the following Examples 1-7:

EXAMPLES Example 1 UV-C Light and Chemical Treatment of Hybrid Corn

Table 1 shows the enhanced harvested corn seed yield of two sowing corn seed hybrids that resulted from three different treatments of UV-C light (36 kJ/m², 240 kJ/m² and 480 kJ/m²) coupled with an additional chemical over-treatment of Maxim XL™, Apron XL™, and Trilex™ before planting. The UV-C light doses selected for chemical over-treatment were within a large range to explore what effect, if any, these treatments on sowing corn seed would have on harvested corn seed yield. The UV-C light treatment was applied at the rate of ½ to each side. The average yield improvement for the 3 treatments on Hybrid #1 was 11.1 bushels per acre of 5.1% greater than control. The average yield improvement for the 3 treatments on Hybrid #2 was 11.4 bushels per acre or 5.4% greater than control. The single best treatment for Hybrid #1 was at 36 kJ/m² plus chemical over-treatment, which was 13.7 bushels acre or 6.3% greater than control. The single best treatment for Hybrid #2 was at 480 kJ/m² plus chemical over-treatment at 15.4 bushels per acre or 7.3% greater than control.

TABLE 1 Corn with Chemical Over-Treatment Corn UV-C Treated Control With Chemical Avg. Yield Avg. Yield Difference Difference Over-treatment Bu./acre Bu./acre Bu./acre Percent Hybrid #1 227.9 216.8 11.1 5.1% Hybrid #2 222.5 211.1 11.4 5.4% Average 225.2 214.0 11.2 5.3%

In conclusion, select doses of UV-C light coupled with chemical over-treatment to sowing corn seed resulted in enhanced yield of harvested seed.

Example 2 UV-C Light and Chemical Treatment of Inbred Corn

Table 2 shows the enhanced harvested corn yield from sowing seeds of a corn inbred treated with a selected treatment of UV-C light (480 kJ/m²) and then over-treated with Maxim XL™, Apron XL™, and Trilex™ before planting. A single dose was selected because the primary purpose of this test was exploratory to determine whether the plant from the treated corn sowing seed tasseled at the same or different time as compared to the control. The secondary purpose for this test was to measure yield. No significant difference to tassel date was observed. However, yield from the treated seed was 13.2 bushels per acre or 11.1% greater than control.

TABLE 2 Corn with Chemical Over-Treatment Corn UV-C Treated Control With Chemical Avg. Yield Avg. Yield Difference Difference Over-treatment Bu./acre Bu./acre Bu./acre Percent Inbred #1 132.6 119.4 13.2 11.1%

In conclusion, the select dose of UV-C coupled with chemical over-treatment to sowing seed resulted in enhance yield of harvested seed.

Example 3 UV-C Light Treatment of Soybean

Table 3 shows the average harvested soybean seed yield for three soybean varieties that were each treated with the same seven different selected treatments of UV-C light before planting. Four of the seven treatments were where ½ of the UV-C light exposure was applied to one side of the seed and then the seeds were turned over for the other ½ of the UV-C light exposure. The dosages for these four treatments were 28 kJ/m², 120 kJ/m², 240 kJ/m² and 480 kJ/m². Three of the seven treatments were where the seeds had the UV-C light exposure applied to one side of the seed. The dosages for these three treatments were 28 kJ/m², 240 kJ/m² and 480 kJ/m². The UV-C light-treated sowing seeds were not chemically over-treated. The UV-C light doses selected for treating sowing soybean seeds with UV-C light and no chemical over-treatment were within a large range to explore what effect, if any, these treatments on sowing seed would have on harvested seed yield. On average, Variety #1 and #3 had slightly negative yields compared to control. Variety #2 on average for the 7 treatments was 4.0 bushels per acre or 6.6% higher than control. The average of all three varieties was slightly higher than control at 63.9 bushels per acre compared to 63.5 bushels per acre for the control.

TABLE 3 Soybean No Chemical Over-Treatment Soybean UV-C Treated Control No Chemical Avg. Yield Avg. Yield Difference Difference Over-treatment Bu./acre Bu./acre Bu./acre Percent Variety #1 65.4 66.2 −0.8 −1.2% Variety #2 64.3 60.3 4.0 6.6% Variety #3 61.9 64.1 −2.2 −3.4% Average 63.9 63.5 0.4 0.6%

In conclusion, Variety #2, on average, responded more favorably to UV-C light treatments than the other two varieties. Additional insight and conclusions from the test results follow in Example 4.

Example 4 Selective UV-C Light Treatment of Soybean

Table 4 shows the harvested soybean seed yield of three soybean varieties. The yields shown are the average of the three best of the seven treatments that were explained in Example 3 as measured by yield of harvested seed. The UV-C light-treated sowing seeds were not over-treated with chemicals. The best treatment for Variety #1 was 240 kJ/m² (2 sides) at 67.6 bushels per acre, which was 1.5 bushels or 2.2% higher than control. The best treatment for Variety #2 was 28 kJ/m² (2 sides) at 68.1 bushels per acre, which was 7.8 bushels per acre or 12.9% higher than control. The best treatment for Variety #3 was 120 kJ/m² (2 sides), which was 2.8 bushels or 4.4% higher than control.

TABLE 4 Soybean No Chemical Over-Treatment; 3 Best Treatments Soybean No Chemical UV-C Treated Control Over-treatment; UV-C Avg. Yield Avg. Yield Difference Difference 3 Best Treatments Treatments Bu./acre Bu./acre Bu./acre Percent Variety #1 S, X1, X3 66.9 66.2 0.7 1.1% Variety #2 E, S, T 66.2 60.3 5.9 9.8% Variety #3 R, T, X3 64.8 64.1 0.7 1.1% Average 66.0 63.5 2.5 3.9%

The UV-C treatment variables are in Table 5.

TABLE 5 Exposure to Different Sides of the Seeds for UV-C Treatments: Reference kJ/m² Seed Treatment Applied S 240 2 SIDES X1 480 1 SIDE X3 28 1 SIDE E 28 2 SIDES T 480 2 SIDES R 120 2 SIDES

In conclusion, all three varieties showed enhanced yield at selected doses of UV-C light without chemical over-treatment. Variety #2's average of its 3 best UV-C light treatments was 66.2 bushels per acre, which was 5.9 bushels per acre of 9.8% higher than control. The other varieties were also on average higher than control. Variety #2 responded best to treatment on both sides of the sowing seed, while the other varieties results were mixed with both one- and two-sided treatment.

Example 5 UV-C Light and Chemical Treatment of Soybean

Table 6 shows the harvested soybean seed yield of three soybean varieties that were each treated with the same seven different selected treatments of UV-C light and then over-treated with Apron Maxx™ before planting. The control for each variety was only treated with Apron Maxx™. Four of the seven treatments were where ½ of the UV-C light exposure was applied to one side of the seed and then the seeds were turned over for the other ½ of the UV-C light exposure. The dosages for these four treatments were 28 kJ/m², 120 kJ/m², 240 kJ/m² and 480 kJ/m². Three of the seven treatments were where the seeds had the UV-C light exposure applied to one side of the seed. The dosages for these three treatments were 28 kJ/m², 240 kJ/m², and 480 kJ/m². The chemical over-treatment was applied after the UV-C light treatment. The UV-C light doses selected for chemical over-treatment were within a large range to explore what effect, if any, these treatments with chemical over-treatment on sowing soybean seed would have on harvested soybean seed yield. Variety #2's average for the 7 treatments was 64.1 bushels per acre or 3.1 bushels or 5.1% higher than control, which was the best. Varieties #1 and #3 had an average yield that was higher than control by 2.8% and 2.4%, respectively.

TABLE 6 Soybean with Chemical Over-Treatment Soybean UV-C Treated Control With Chemical Avg. Yield Avg. Yield Difference Difference Over-treatment Bu./acre Bu./acre Bu./acre Percent Variety #1 65.3 63.5 1.8 2.8% Variety #2 64.1 61.0 3.1 5.1% Variety #3 64.0 62.5 1.5 2.4% Average 64.5 62.3 2.2 3.5%

In conclusion, all three varieties on averaged showed enhanced yield from UV-C light treatment coupled with chemical over-treatment. Additional insight and conclusions from the test results follow in Example 6.

Example 6 Selective UV-C Light and Chemical Treatment of Soybean

Table 7 shows the harvested soybean seed yield of three soybean varieties. The yield shown is the average of the three best of the seven treatments that were explained in Example 5 as measured by yield of harvested seed. The UV-C light-treated sowing seeds were over-treated with Apron Maxx™ after being treated with UV-C light. Variety #2 on average yield was 66.6 bushels per acre, 5.6 bushels or 9.2% higher than control. Variety #3 on average yield was 66.9 bushels per acre, 4.4 bushels or 7.0% higher than control. Variety #1 on average yield was 67.5 bushels per acre, 4.0 bushels or 6.3% higher than control. The best treatment for all three varieties was 240 kJ/m² applied to 1 side of the sowing seed: Variety #1's yield was 70.6 bushels or 7.1 bushels per acre or 11.2% higher than control; Variety #2's yield was 68.7 bushels or 7.7 bushels per acre or 12.6% higher than control; and Variety #3's yield was 67.4 bushels per acre or 4.9 bushels or 7.8% higher than control.

TABLE 7 Soybean with Chemical Over-Treatment 3 Best Treatments Soybean With Chemical UV-C Treated Control Over-treatment UV-C Avg. Yield Avg. Yield Difference Difference 3 Best Treatments Treatments Bu./acre Bu./acre Bu./acre Percent Variety #1 X2, T, X3 67.5 63.5 4.0 6.3% Variety #2 X2, R, T 66.6 61.0 5.6 9.2% Variety #3 X2, R, E 66.9 62.5 4.4 7.0% Average 67.0 62.3 4.7 7.5%

TABLE 8 Exposure to Different Sides of the Seeds for UV-C Treatments: Reference kJ/m² Seed Treatment Applied X2 240 1 SIDE T 480 2 SIDES X3 28 1 SIDE R 120 2 SIDES E 28 2 SIDES

In conclusion, all three soybean varieties that were tested showed enhanced yield to selected dosages of UV-C light coupled with chemical over-treatment. All three varieties that were tested responded with increased yield, as measured by enhanced yield of harvested seed, to 240 kJ/m² applied to a single side of the sowing soybean seed.

Example 7 Selective UV-C Light and Chemical Treatment of Wheat

Table 9 shows the harvested wheat seed yield of a single wheat variety with four different UV-C light treatments (80 kJ/m², 100 kJ/m², 140 kJ/m² and 240 kJ/m²) coupled with chemical over-treatment with Dividend Extreme™ compared to control with no UV-C light treatment, but with chemical over-treatment. The UV-C light doses selected for chemical over-treatment were within a large range to explore what effect, if any, these treatments on sowing wheat seed would have on harvested wheat seed yield. The treatment methodology was such that ½ of the treatment was applied to one side of the seeds and then the seeds were turned over to apply the second ½ of the treatment to the other side of the seeds. The UV-C light doses selected for treating sowing wheat seed were within a large range to explore what effect, if any, these treatments, coupled with chemical over-treatment, had on the yield of harvested wheat seed. A significant yield enhancing effect for wheat was obtained with 140 kJ/m² treatment with chemical over-treatment that averaged 6.1 bushels higher or 112.5% of control. The enhanced yield was statistically significant. Further optimization can be readily performed for example, by treatments less than 80 kJ/m², greater than 240 kJ/m², and between the large treatment intervals.

TABLE 9 Selective UV-C Treatment of Wheat with Chemical Over-treatment Variety Treatment kJ/m² Yield bu./acre % of control Branson none-control 53.4 n/a Branson  80 53.0 99.2 Branson 100 52.3 97.9 Branson 140 60.1 112.5 Branson 240 51.2 95.9

In conclusion, a select treatment of UV-C light (140 kJ/m²) coupled with chemical over-treatment to sowing wheat seed, resulted in enhanced yield of harvested wheat seed.

Materials and Methods

The corn hybrids were planted in 6 replicated blocks at one location and the inbred was planted in two replicated blocks at one location. The sowing seeds were planted in thirty-inch rows on ground prepared following conventional tillage practices. The prior year crop on this ground was soybeans. Corn was harvested 5-months after planting.

The soybean varieties were planted in 3 replicated blocks at one location. The sowing seeds were planted in thirty-inch rows on ground prepared following conventional tillage practices. The prior year crop on this ground was soybeans. Soybean was harvested about 5-months after planting.

The wheat variety was planted in 3 replicated blocks at one location. The sowing seeds were drilled in rows that were 6 feet 7 inches wide by 18 feet long on ground prepared following conventional tillage practices. The prior year crop on this ground was soybeans. Wheat was harvested about 8-months after planting.

Method of UV-C Treatment: Doses of UV-C light were administered to corn, soybean, and wheat sowing seed by placing a monolayer of the seed randomly oriented on a flat tray 30.5×45.7 cm. The tray with the seeds was then placed under a grouping of 5 UV lamps with stainless-steel reflectors that were 12.7 cm above the tray. The five UV-C emitting lamps (Model UF-36-SR; American Ultra Violet Co.) that produced 90% quasi-monochromatic UV at 254 nm) were mounted 2 cm apart over the trays. UV-C light emitted by the lamps was measured 12.7 cm below the lamp surface with a UVX radiometer (UVP, Inc., San Gabriel, Calif.). Treatments were administered either to one side of the seed or to both sides. In order to turn the seeds over and treat the opposite side an additional tray was place on top of the treated seeds holding them in place while the two trays were turned over exposing the opposite side of the seeds for treatment. It is within the scope of this disclosure to expose various seed surfaces (sides and ends) to UV-C light at various doses that will elicit the hormetic response.

Method of Chemical Over-treatment: The Maxim XL™, Apron XL™, and Trilex™ was applied to each treatment lot of corn by using a slurry in a rotating-drum seed treater. The application rate was the standard rate recommend by the manufacturer. The Apron Maxx was applied to each treatment lot of soybeans by using a slurry in a rotating-drum seed treater. The application rate was the standard rate recommended by the manufacturer. The Dividend Extreme™ was applied to each treatment lot of wheat by using a commercially available small lab scale mist seed treater. The application rate was the standard rate recommended by the manufacturer.

Method of Planting: The corn and soybeans were planted by a special built row crop test plot planter set up for 30 inch rows. Some of the key features of this type of planter include the capability to plant relatively small areas with a very high degree of accuracy and with significant amount of computer tracked data for testing control. The wheat was drilled with a special built planting drill, which also has the key planting accuracy and data control features.

Method of Harvesting: All test plots were harvested using a combine specialized for harvesting test plots. A key special feature of the combine is the data collection system, which records weight, moisture and test weight of the harvested seed from each test plot.

Method of Determining Optimum UV Light Treatments: For each type of UV-C light delivery system optimal doses can be readily determined for the type of seed, and possibly varieties or hybrids within seed types. According to the hormetic model, as the dosage of a stressor such as UV-C is increased there will be an optimum dosage that will give a maximum beneficial response, as measured by the yield of harvested seed. The optimum treatment is in the range of about 0.025-480 kJ/m². Optimal treatments are determined through treating sowing seed with UV-C light and field testing treated seed within this range for harvested seed yield. To expedite the determination of optimal treatments and to do so at a lower cost, treating sowing seeds with UV-C light in the range of 0.025-480 kJ/m² and planting them in a greenhouse where effects of the irradiation (positive and negative) on seedling growth can be observed narrows the number of necessary field trials. Further, by growing plants from UV-C treated seed in the greenhouse, inoculating them with a pest, such as Fusarium sp., and then observing the effects of the irradiation on disease development the number of field trials necessary for identifying optimal doses is further narrowed. 

1. A method of increasing the yield of harvested plants seeds, the method comprising treating plant sowing seeds with an effective dose of ultraviolet (UV) light.
 2. The method of claim 1, wherein the UV light comprises UV-C.
 3. The method of claim 1, wherein the UV light is pulsed UV.
 4. The method of claim 1, wherein the effective dose range from about 0.025-480 kJ/m².
 5. The method of claim 3, wherein the pulsed UV light comprises a high peak power of wavelengths from about 200 to 1100 nm.
 6. The method of claim 5, wherein the pulsed UV light is substantially in the UV-C range of 200-280 nm.
 7. The method of claim 3, wherein the pulsed UV durations range from picoseconds to microseconds at 1-1900 mJ/cm².
 8. The method of claim 1, wherein the harvested plant seed yield increase is by about 5%-10% when compared to yield from harvested untreated control seeds.
 9. The method of claim 1 further comprising treating the sowing seeds with an agent.
 10. The method of claim 9, wherein the agent is selected from the group consisting of pesticides, insecticides, and fungicides.
 11. The method of claim 1, wherein the sowing seeds are from a crop plant.
 12. The method of claim 1, wherein the plant sowing seeds are selected from the group of plants consisting of soybean, corn, wheat, rice, cotton, sorghum, canola, barley, and vegetable.
 13. The method of claim 1, wherein the UV light treatment is applied to the sowing seeds on one side or two sides or the ends or a combination thereof.
 14. The method of claim 1, wherein the UV light is from a pulsed laser light source.
 15. A method of treating a plurality of plant sowing seeds with a physical stressor to induce a hormetic response, wherein the physical stressor is UV light and the hormetic response is increased yield of harvested plant seeds.
 16. The method of claim 15, wherein the UV light is pulsed.
 17. A plurality of ultraviolet light-treated plant sowing seeds such that the seeds result in plants whose harvested plant seed yield is increased, and wherein the UV light treatment is effective to induce a hormetic response.
 18. The ultraviolet light-treated plant sowing seeds of claim 17, wherein the seeds are selected from the group consisting of soybean, corn, wheat, rice, cotton, sorghum, canola and vegetable seeds.
 19. The ultraviolet light-treated plant sowing seeds of claim 17, wherein the UV light is pulsed.
 20. The ultraviolet light-treated plant sowing seeds of claim 17, wherein the UV light is UV-C with an effective dose range from about 0.025-480 kJ/m².
 21. A plurality of UV-C light-treated sowing plant seeds, wherein the UV-C light is effective to induce an increased yield of the harvested plant seeds.
 22. The plant sowing seeds of claim 21, further comprising a treatment with an agent selected from the group consisting of pesticides, insecticides, and fungicides.
 23. The plant sowing seeds of claim 21, wherein the seeds are from a crop plant.
 24. The plant sowing seeds of claim 21, wherein the plant seeds are selected from the group consisting of soybean, corn, wheat, rice, cotton, sorghum, canola, and barley seeds.
 25. The plant sowing seeds of claim 21, wherein the UV-C light comprises an effective dose range from about 0.025-480 kJ/m². 